/*

 * rdtarga.c

 *

 * Copyright (C) 1991-1995, Thomas G. Lane.

 * This file is part of the Independent JPEG Group's software.

 * For conditions of distribution and use, see the accompanying README file.

 *

 * This file contains routines to read input images in Targa format.

 *

 * These routines may need modification for non-Unix environments or

 * specialized applications.  As they stand, they assume input from

 * an ordinary stdio stream.  They further assume that reading begins

 * at the start of the file; start_input may need work if the

 * user interface has already read some data (e.g., to determine that

 * the file is indeed Targa format).

 *

 * Based on code contributed by Lee Daniel Crocker.

 */



#include "cdjpeg.h"		/* Common decls for cjpeg/djpeg applications */



#ifdef TARGA_SUPPORTED





/* Macros to deal with unsigned chars as efficiently as compiler allows */



#ifdef HAVE_UNSIGNED_CHAR

typedef unsigned char U_CHAR;

#define UCH(x)	((int) (x))

#else /* !HAVE_UNSIGNED_CHAR */

#ifdef CHAR_IS_UNSIGNED

typedef char U_CHAR;

#define UCH(x)	((int) (x))

#else

typedef char U_CHAR;

#define UCH(x)	((int) (x) & 0xFF)

#endif

#endif /* HAVE_UNSIGNED_CHAR */





#define	ReadOK(file,buffer,len)	(JFREAD(file,buffer,len) == ((size_t) (len)))





/* Private version of data source object */



typedef struct _tga_source_struct * tga_source_ptr;



typedef struct _tga_source_struct {

  struct cjpeg_source_struct pub; /* public fields */



  j_compress_ptr cinfo;		/* back link saves passing separate parm */



  JSAMPARRAY colormap;		/* Targa colormap (converted to my format) */



  jvirt_sarray_ptr whole_image;	/* Needed if funny input row order */

  JDIMENSION current_row;	/* Current logical row number to read */



  /* Pointer to routine to extract next Targa pixel from input file */

  JMETHOD(void, read_pixel, (tga_source_ptr sinfo));



  /* Result of read_pixel is delivered here: */

  U_CHAR tga_pixel[4];



  int pixel_size;		/* Bytes per Targa pixel (1 to 4) */



  /* State info for reading RLE-coded pixels; both counts must be init to 0 */

  int block_count;		/* # of pixels remaining in RLE block */

  int dup_pixel_count;		/* # of times to duplicate previous pixel */



  /* This saves the correct pixel-row-expansion method for preload_image */

  JMETHOD(JDIMENSION, get_pixel_rows, (j_compress_ptr cinfo,

				       cjpeg_source_ptr sinfo));

} tga_source_struct;





/* For expanding 5-bit pixel values to 8-bit with best rounding */



static const UINT8 c5to8bits[32] = {

    0,   8,  16,  25,  33,  41,  49,  58,

   66,  74,  82,  90,  99, 107, 115, 123,

  132, 140, 148, 156, 165, 173, 181, 189,

  197, 206, 214, 222, 230, 239, 247, 255

};







LOCAL int

read_byte (tga_source_ptr sinfo)

/* Read next byte from Targa file */

{

  register FILE *infile = sinfo->pub.input_file;

  register int c;



  if ((c = getc(infile)) == EOF)

    ERREXIT(sinfo->cinfo, JERR_INPUT_EOF);

  return c;

}





LOCAL void

read_colormap (tga_source_ptr sinfo, int cmaplen, int mapentrysize)

/* Read the colormap from a Targa file */

{

  int i;



  /* Presently only handles 24-bit BGR format */

  if (mapentrysize != 24)

    ERREXIT(sinfo->cinfo, JERR_TGA_BADCMAP);



  for (i = 0; i < cmaplen; i++) {

    sinfo->colormap[2][i] = (JSAMPLE) read_byte(sinfo);

    sinfo->colormap[1][i] = (JSAMPLE) read_byte(sinfo);

    sinfo->colormap[0][i] = (JSAMPLE) read_byte(sinfo);

  }

}





/*

 * read_pixel methods: get a single pixel from Targa file into tga_pixel[]

 */



LOCAL void

read_non_rle_pixel (tga_source_ptr sinfo)

/* Read one Targa pixel from the input file; no RLE expansion */

{

  register FILE *infile = sinfo->pub.input_file;

  register int i;



  for (i = 0; i < sinfo->pixel_size; i++) {

    sinfo->tga_pixel[i] = (U_CHAR) getc(infile);

  }

}





LOCAL void

read_rle_pixel (tga_source_ptr sinfo)

/* Read one Targa pixel from the input file, expanding RLE data as needed */

{

  register FILE *infile = sinfo->pub.input_file;

  register int i;



  /* Duplicate previously read pixel? */

  if (sinfo->dup_pixel_count > 0) {

    sinfo->dup_pixel_count--;

    return;

  }



  /* Time to read RLE block header? */

  if (--sinfo->block_count < 0) { /* decrement pixels remaining in block */

    i = read_byte(sinfo);

    if (i & 0x80) {		/* Start of duplicate-pixel block? */

      sinfo->dup_pixel_count = i & 0x7F; /* number of dups after this one */

      sinfo->block_count = 0;	/* then read new block header */

    } else {

      sinfo->block_count = i & 0x7F; /* number of pixels after this one */

    }

  }



  /* Read next pixel */

  for (i = 0; i < sinfo->pixel_size; i++) {

    sinfo->tga_pixel[i] = (U_CHAR) getc(infile);

  }

}





/*

 * Read one row of pixels.

 *

 * We provide several different versions depending on input file format.

 */





METHODDEF JDIMENSION

get_8bit_gray_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

/* This version is for reading 8-bit grayscale pixels */

{

  tga_source_ptr source = (tga_source_ptr) sinfo;

  register JSAMPROW ptr;

  register JDIMENSION col;

  

  ptr = source->pub.buffer[0];

  for (col = cinfo->image_width; col > 0; col--) {

    (*source->read_pixel) (source); /* Load next pixel into tga_pixel */

    *ptr++ = (JSAMPLE) UCH(source->tga_pixel[0]);

  }

  return 1;

}



METHODDEF JDIMENSION

get_8bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

/* This version is for reading 8-bit colormap indexes */

{

  tga_source_ptr source = (tga_source_ptr) sinfo;

  register int t;

  register JSAMPROW ptr;

  register JDIMENSION col;

  register JSAMPARRAY colormap = source->colormap;



  ptr = source->pub.buffer[0];

  for (col = cinfo->image_width; col > 0; col--) {

    (*source->read_pixel) (source); /* Load next pixel into tga_pixel */

    t = UCH(source->tga_pixel[0]);

    *ptr++ = colormap[0][t];

    *ptr++ = colormap[1][t];

    *ptr++ = colormap[2][t];

  }

  return 1;

}



METHODDEF JDIMENSION

get_16bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

/* This version is for reading 16-bit pixels */

{

  tga_source_ptr source = (tga_source_ptr) sinfo;

  register int t;

  register JSAMPROW ptr;

  register JDIMENSION col;

  

  ptr = source->pub.buffer[0];

  for (col = cinfo->image_width; col > 0; col--) {

    (*source->read_pixel) (source); /* Load next pixel into tga_pixel */

    t = UCH(source->tga_pixel[0]);

    t += UCH(source->tga_pixel[1]) << 8;

    /* We expand 5 bit data to 8 bit sample width.

     * The format of the 16-bit (LSB first) input word is

     *     xRRRRRGGGGGBBBBB

     */

    ptr[2] = (JSAMPLE) c5to8bits[t & 0x1F];

    t >>= 5;

    ptr[1] = (JSAMPLE) c5to8bits[t & 0x1F];

    t >>= 5;

    ptr[0] = (JSAMPLE) c5to8bits[t & 0x1F];

    ptr += 3;

  }

  return 1;

}



METHODDEF JDIMENSION

get_24bit_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

/* This version is for reading 24-bit pixels */

{

  tga_source_ptr source = (tga_source_ptr) sinfo;

  register JSAMPROW ptr;

  register JDIMENSION col;

  

  ptr = source->pub.buffer[0];

  for (col = cinfo->image_width; col > 0; col--) {

    (*source->read_pixel) (source); /* Load next pixel into tga_pixel */

    *ptr++ = (JSAMPLE) UCH(source->tga_pixel[2]); /* change BGR to RGB order */

    *ptr++ = (JSAMPLE) UCH(source->tga_pixel[1]);

    *ptr++ = (JSAMPLE) UCH(source->tga_pixel[0]);

  }

  return 1;

}



/*

 * Targa also defines a 32-bit pixel format with order B,G,R,A.

 * We presently ignore the attribute byte, so the code for reading

 * these pixels is identical to the 24-bit routine above.

 * This works because the actual pixel length is only known to read_pixel.

 */



#define get_32bit_row  get_24bit_row





/*

 * This method is for re-reading the input data in standard top-down

 * row order.  The entire image has already been read into whole_image

 * with proper conversion of pixel format, but it's in a funny row order.

 */



METHODDEF JDIMENSION

get_memory_row (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

{

  tga_source_ptr source = (tga_source_ptr) sinfo;

  JDIMENSION source_row;



  /* Compute row of source that maps to current_row of normal order */

  /* For now, assume image is bottom-up and not interlaced. */

  /* NEEDS WORK to support interlaced images! */

  source_row = cinfo->image_height - source->current_row - 1;



  /* Fetch that row from virtual array */

  source->pub.buffer = (*cinfo->mem->access_virt_sarray)

    ((j_common_ptr) cinfo, source->whole_image,

     source_row, (JDIMENSION) 1, FALSE);



  source->current_row++;

  return 1;

}





/*

 * This method loads the image into whole_image during the first call on

 * get_pixel_rows.  The get_pixel_rows pointer is then adjusted to call

 * get_memory_row on subsequent calls.

 */



METHODDEF JDIMENSION

preload_image (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

{

  tga_source_ptr source = (tga_source_ptr) sinfo;

  JDIMENSION row;

  cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;



  /* Read the data into a virtual array in input-file row order. */

  for (row = 0; row < cinfo->image_height; row++) {

    if (progress != NULL) {

      progress->pub.pass_counter = (long) row;

      progress->pub.pass_limit = (long) cinfo->image_height;

      (*progress->pub.progress_monitor) ((j_common_ptr) cinfo);

    }

    source->pub.buffer = (*cinfo->mem->access_virt_sarray)

      ((j_common_ptr) cinfo, source->whole_image, row, (JDIMENSION) 1, TRUE);

    (*source->get_pixel_rows) (cinfo, sinfo);

  }

  if (progress != NULL)

    progress->completed_extra_passes++;



  /* Set up to read from the virtual array in unscrambled order */

  source->pub.get_pixel_rows = get_memory_row;

  source->current_row = 0;

  /* And read the first row */

  return get_memory_row(cinfo, sinfo);

}





/*

 * Read the file header; return image size and component count.

 */



METHODDEF void

start_input_tga (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

{

  tga_source_ptr source = (tga_source_ptr) sinfo;

  U_CHAR targaheader[18];

  int idlen, cmaptype, subtype, flags, interlace_type, components;

  unsigned int width, height, maplen;

  boolean is_bottom_up;



#define GET_2B(offset)	((unsigned int) UCH(targaheader[offset]) + \

			 (((unsigned int) UCH(targaheader[offset+1])) << 8))



  if (! ReadOK(source->pub.input_file, targaheader, 18))

    ERREXIT(cinfo, JERR_INPUT_EOF);



  /* Pretend "15-bit" pixels are 16-bit --- we ignore attribute bit anyway */

  if (targaheader[16] == 15)

    targaheader[16] = 16;



  idlen = UCH(targaheader[0]);

  cmaptype = UCH(targaheader[1]);

  subtype = UCH(targaheader[2]);

  maplen = GET_2B(5);

  width = GET_2B(12);

  height = GET_2B(14);

  source->pixel_size = UCH(targaheader[16]) >> 3;

  flags = UCH(targaheader[17]);	/* Image Descriptor byte */



  is_bottom_up = ((flags & 0x20) == 0);	/* bit 5 set => top-down */

  interlace_type = flags >> 6;	/* bits 6/7 are interlace code */



  if (cmaptype > 1 ||		/* cmaptype must be 0 or 1 */

      source->pixel_size < 1 || source->pixel_size > 4 ||

      (UCH(targaheader[16]) & 7) != 0 || /* bits/pixel must be multiple of 8 */

      interlace_type != 0)	/* currently don't allow interlaced image */

    ERREXIT(cinfo, JERR_TGA_BADPARMS);

  

  if (subtype > 8) {

    /* It's an RLE-coded file */

    source->read_pixel = read_rle_pixel;

    source->block_count = source->dup_pixel_count = 0;

    subtype -= 8;

  } else {

    /* Non-RLE file */

    source->read_pixel = read_non_rle_pixel;

  }



  /* Now should have subtype 1, 2, or 3 */

  components = 3;		/* until proven different */

  cinfo->in_color_space = JCS_RGB;



  switch (subtype) {

  case 1:			/* Colormapped image */

    if (source->pixel_size == 1 && cmaptype == 1)

      source->get_pixel_rows = get_8bit_row;

    else

      ERREXIT(cinfo, JERR_TGA_BADPARMS);

    TRACEMS2(cinfo, 1, JTRC_TGA_MAPPED, width, height);

    break;

  case 2:			/* RGB image */

    switch (source->pixel_size) {

    case 2:

      source->get_pixel_rows = get_16bit_row;

      break;

    case 3:

      source->get_pixel_rows = get_24bit_row;

      break;

    case 4:

      source->get_pixel_rows = get_32bit_row;

      break;

    default:

      ERREXIT(cinfo, JERR_TGA_BADPARMS);

      break;

    }

    TRACEMS2(cinfo, 1, JTRC_TGA, width, height);

    break;

  case 3:			/* Grayscale image */

    components = 1;

    cinfo->in_color_space = JCS_GRAYSCALE;

    if (source->pixel_size == 1)

      source->get_pixel_rows = get_8bit_gray_row;

    else

      ERREXIT(cinfo, JERR_TGA_BADPARMS);

    TRACEMS2(cinfo, 1, JTRC_TGA_GRAY, width, height);

    break;

  default:

    ERREXIT(cinfo, JERR_TGA_BADPARMS);

    break;

  }



  if (is_bottom_up) {

    /* Create a virtual array to buffer the upside-down image. */

    source->whole_image = (*cinfo->mem->request_virt_sarray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE, FALSE,

       (JDIMENSION) width * components, (JDIMENSION) height, (JDIMENSION) 1);

    if (cinfo->progress != NULL) {

      cd_progress_ptr progress = (cd_progress_ptr) cinfo->progress;

      progress->total_extra_passes++; /* count file input as separate pass */

    }

    /* source->pub.buffer will point to the virtual array. */

    source->pub.buffer_height = 1; /* in case anyone looks at it */

    source->pub.get_pixel_rows = preload_image;

  } else {

    /* Don't need a virtual array, but do need a one-row input buffer. */

    source->whole_image = NULL;

    source->pub.buffer = (*cinfo->mem->alloc_sarray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE,

       (JDIMENSION) width * components, (JDIMENSION) 1);

    source->pub.buffer_height = 1;

    source->pub.get_pixel_rows = source->get_pixel_rows;

  }

  

  while (idlen--)		/* Throw away ID field */

    (void) read_byte(source);



  if (maplen > 0) {

    if (maplen > 256 || GET_2B(3) != 0)

      ERREXIT(cinfo, JERR_TGA_BADCMAP);

    /* Allocate space to store the colormap */

    source->colormap = (*cinfo->mem->alloc_sarray)

      ((j_common_ptr) cinfo, JPOOL_IMAGE, (JDIMENSION) maplen, (JDIMENSION) 3);

    /* and read it from the file */

    read_colormap(source, (int) maplen, UCH(targaheader[7]));

  } else {

    if (cmaptype)		/* but you promised a cmap! */

      ERREXIT(cinfo, JERR_TGA_BADPARMS);

    source->colormap = NULL;

  }



  cinfo->input_components = components;

  cinfo->data_precision = 8;

  cinfo->image_width = width;

  cinfo->image_height = height;

}





/*

 * Finish up at the end of the file.

 */



METHODDEF void

finish_input_tga (j_compress_ptr cinfo, cjpeg_source_ptr sinfo)

{

  /* no work */

}





/*

 * The module selection routine for Targa format input.

 */



GLOBAL cjpeg_source_ptr

jinit_read_targa (j_compress_ptr cinfo)

{

  tga_source_ptr source;



  /* Create module interface object */

  source = (tga_source_ptr)

      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

				  SIZEOF(tga_source_struct));

  source->cinfo = cinfo;	/* make back link for subroutines */

  /* Fill in method ptrs, except get_pixel_rows which start_input sets */

  source->pub.start_input = start_input_tga;

  source->pub.finish_input = finish_input_tga;



  return (cjpeg_source_ptr) source;

}



#endif /* TARGA_SUPPORTED */

